As soft materials composed of polyolefins which are excellent in flexibility, heat resistance and transparency and have environmental suitability and hygienic qualities, propylene-based elastomers containing propylene as a main component are known in recent years (see, for example, patent documents 1, 2 and 3).
Although the range of uses of such propylene-based elastomers is increasing at present, performance of propylene-based elastomers obtained in the prior art is not satisfactory, and further improvements in the aforesaid properties, such as flexibility, heat resistance and transparency, have been desired. Particularly in the prior art, practical heat resistance is insufficient, and therefore, there occurs a problem that surface stickiness develops when such elastomers are exposed to high temperatures for a long period of time.
Moreover, resin compositions containing polypropylene as a main component and their products have been applied to uses of a wide range, such as electric/electronic equipment parts, industrial materials, furniture, stationary, daily necessaries/miscellaneous goods, containers/packaging materials, toys, leisure goods, and medical supplies. On the other hand, there are known techniques for adding various flexibilizing materials in order to improve flexibility and impact resistance of the resin compositions containing polypropylene as a main component and their products, and it is known that by the use of a propylene-based polymer composition comprising the aforesaid propylene/ethylene/α-olefin copolymer of specific composition as an additive, flexibility, transparency, impact resistance, whitening resistance, etc. of the polypropylene resin compositions and their products can be improved (see patent documents 2 and 4).
Even in these techniques, however, the improvements are not satisfactory occasionally, and for example, an evil of occurrence of surface stickiness on exposure to high temperatures for a long period of time has been found similarly to the aforesaid case.    Patent document 1: International Publication No. WO2004/106430 A1    Patent document 2: Japanese Patent laid-Open Publication No. 186664/2007    Patent document 3: Japanese Patent laid-Open Publication No. 309982/1997    Patent document 4: Japanese Patent No. 3344842